The European Journal of Orthodontics Advance Access originally published online on July 2, 2007
The European Journal of Orthodontics 2007 29(4):398-403; doi:10.1093/ejo/cjm010
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Cervical column morphology related to head posture, cranial base angle, and condylar malformation
* Department of Orthodontics, School of Dentistry, Faculty of Health Sciences, University of Copenhagen Department of Orthodontics, Faculty of Health Sciences, University of Aarhus
** Department of Orthodontics, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Denmark
Address for correspondence Liselotte Sonnesen, Department of Orthodontics, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, 20 Nørre Allé, DK-2200 Copenhagen N, Denmark E-mail: lls{at}odont.ku.dk
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Summary |
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The present study describes the cervical column as related to head posture, cranial base, and mandibular condylar hypoplasia. Two groups were included in the study. The ‘normal’ sample comprised 21 subjects, 15 females aged 23–40 years (mean 29.2 years), and six males aged 25–44 years (mean 32.8 years) with neutral occlusion and normal craniofacial morphology. The condylar hypoplasia group comprised the lateral profile radiographs of 11 patients, eight females, and three males, aged 12–38 years (mean 21.6 years). For each individual, a profile radiograph was taken to perform a visual assessment of the morphology of the cervical column. For the normal group only, the profile radiographs were taken in the standardized head posture to measure the head posture and the cranial base angle.
Cervical column: Morphological deviations of the cervical column occurred significantly more often in the subjects with condylar hypoplasia compared with the normal group (P < 0.05 and P < 0.01, respectively). The pattern of morphological deviations was significantly more severe in the subjects with condylar hypoplasia compared with the normal group (P < 0.01).
Cervical column related to head posture and cranial base: The cervicohorizontal and cranial base angles were statistically larger in females than in males (P < 0.05 and P < 0.01, respectively). No statistically significant age differences were found. Only in females was the cervical lordosis angle (OPT/CVT, P < 0.01), the inclination of the upper cervical spine (OPT/HOR, P < 0.05), and the cranial base angle (n–s–ba, P < 0.05) significantly positively correlated with fusion of the cervical column. These associations were not due to the effect of age.
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Introduction |
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Dimensions of the first cervical vertebra (C1), atlas, as well as the posture of the head and neck are associated with factors such as craniofacial morphology, including the cranial base (Solow and Tallgren, 1976
; Opdebeek et al., 1978; Marcotte, 1981; von Treuenfels, 1981; Solow et al., 1984; Hellsing et al., 1987; Huggare, 1987, 1991; Sandikcioglu et al., 1994; Huggare and Houghton, 1996), upper airway space (Solow et al., 1984, 1996; Wenzel et al., 1985), to some extent, occlusion (Rocabado et al., 1982; Huggare, 1991; Huggare and Harkness, 1993; Solow and Sonnesen, 1998), and temporomandibular disorders (Kritsineli and Shim, 1992; Hackney et al., 1993; Watson and Trott, 1993; Lee et al., 1995; Sonnesen, 1997; Sonnesen et al., 2001; Visscher et al., 2002). Furthermore, head posture is associated with the development and function of the dentofacial structures (Solow and Siersbæk-Nielsen, 1986, 1992; Sonnesen, 1997; Sonnesen et al., 2001; Solow and Sandham, 2002). Previous research has also focused on associations between the dimensions of C1, atlas, and craniocervical posture (Huggare, 1991; Sandikcioglu et al., 1994). However, no previous studies have described associations between head posture and morphology of C1–C5 or between the cranial base and the morphology of C1–C5 in adults with neutral occlusion and normal craniofacial morphology.
Morphological deviations of the upper cervical vertebrae have been investigated in relation to craniofacial aberrations and syndromes. Malformations of the upper cervical vertebrae have been described in patients with cleft lip and/or palate (Sandham, 1986; Horswell, 1991; Ugar and Semb, 2001). The association between the cervical vertebrae and the maxilla is caused by a developmental fault of the mesenchyme (Sandham, 1986; Ugar and Semb, 2001), as the areas are dependent on the same or similar paraaxial mesoderm (Kjær et al., 1994; Kjær, 1995, 1998; Sadler, 2005). While the associations are well described for the maxilla, no studies have investigated deviations of the cervical vertebrae in patients with mandibular condylar hypoplasia.
The aims of the present study were, therefore, (1) to describe the morphology of the cervical column in adult subjects with neutral occlusion and normal craniofacial morphology and in patients with mandibular condylar hypoplasia, and (2) to examine association between the various morphological characteristics of the cervical column, the cranial base angle, and the posture of the head and neck.
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Subjects |
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The collection of subjects with neutral occlusion and normal craniofacial morphology was approved by the Scientific Ethical Committee for Aarhus (Ref. no. 2002 0040). The study comprised two groups.
The ‘normal’ group were 21 subjects (15 females and six males). The females were aged 23–40 years (mean 29.2 years) and the males 25–44 years (mean 32.8 years). The subjects were either students or staff members at the School of Dentistry, Aarhus University. The selection criteria was a neutral occlusion or minor malocclusion not requiring orthodontic treatment according to the Danish procedure for screening the population for malocclusion entailing health risks (Danish Ministry of Health, 1990; Solow, 1995). Furthermore, the sagittal and vertical jaw relationship should be within 1 standard deviation according to the standard material described by Björk (1947), assessed on lateral radiographs of each individual. None of the subjects had obstructions of the upper airways, craniofacial anomalies, or systemic muscle or joint disorders or had undergone orthodontic treatment.
The group with condylar hypoplasia was obtained from the original files of Professor Arne Björk, Department of Orthodontics, University of Copenhagen. One of these files was marked ‘condylar hypoplasia’ and contained lateral profile radiographs of 11 patients, eight females, and three males, age 12–38 years (mean age 21.6 years) with mandibular condylar hypoplasia.
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Methods |
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Morphology of the cervical vertebrae
Visual assessment of the cervical column consisted of C1–C5 units that are normally seen on a standardized lateral skull radiograph. Characteristics of the cervical column were classified according to Sandham (1986) and divided into two categories as ‘posterior arch deficiency’ and ‘fusion anomalies’. Posterior arch deficiency consisted of partial cleft and dehiscence and fusion anomalies of fusion, block fusion, and occipitalization.
Head posture and cranial base angle
For the normal group, the profile radiographs were obtained with the teeth in occlusion and in a standardized head posture, the mirror position, as described by Siersbæk-Nielsen and Solow (1982). The radiographs were taken at the Department of Oral Radiology, School of Dentistry, Aarhus University, Denmark, in a Bucky Conds cephalometer (Petersen and Schmidt, Copenhagen, Denmark) with a film-to-focus distance of 180 cm and a film-to-median plane distance of 10 cm. No correction was made for the constant linear enlargement of 5.6 per cent. A plumb-line was hung from the ceiling to mark the true vertical line on the radiographs. The digital radiographic system was photostimulable phosphor plate, Digora (Soredex, Helsinki, Finland), placed in a traditional cassette without an intensifying screen. The reference points were marked and digitized in PorDios for Windows, version 6 (Institute for Orthodontic Computer Science, Middelfart, Denmark; Figure 1), and 10 variables representing the craniovertical, craniocervical, and cervicohorizontal postural relationships; the curvature of the cervical column; and the cranial base angle were calculated. A list of the variables is shown in Table 1.
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For the condylar hypoplasia group, the profile radiographs were collected before 1982 and were not taken in a standardized head posture. The measurements for head posture were therefore not included in this part of the study. The profile radiographs were taken in a cephalostat with a film-to-focus distance of 180 cm and a film-to-median plane distance of 10 cm. No correction was made for the constant linear enlargement of 5.6 per cent (Björk, 1975
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Reliability
The reliability of the visual assessment of the morphological characteristics of the cervical vertebrae units was determined by inter-observer examinations between two authors (LS and IK). The inter-observer examinations showed ‘very good’ agreement (
= 0.82) as assessed by the kappa coefficient (Cohen, 1960).
The reliability of the variables describing head posture and cranial base angle was assessed by remeasurement of 20 lateral radiographs selected at random from the previously recorded radiographs. The radiographs were again digitized, and the differences between the two sets of recordings were calculated. No significant differences between the two sets of recordings were found. The method errors ranged from 0.09 to 0.69 degrees (Dahlberg, 1940) and the reliability coefficients from 0.99 to 1.00 (Houston, 1983).
Statistical methods
The normality of the distributions was assessed by the parameters of skewness and kurtosis and by Shapiro–Wilks W-test. The postural variables and cranial base angle were normally distributed. For the postural variables and cranial base angle, the effect of age was assessed by linear regression analysis, and for the occurrence of morphological characteristics of the cervical column by logistic regression analysis. Differences in the means of the postural variables and the cranial base between genders were assessed by unpaired t-test. Differences in the occurrence of morphological characteristics of the cervical column between genders and between the two groups were assessed by Fisher's exact test. Associations between morphology of the cervical column, head posture, and cranial base were expressed in terms of Spearman rank order correlation coefficients and tested for the possible effect of age by multiple regression analyses. The results from the tests were considered to be significant at P values below 0.05. The statistical analyses were performed using the Statistical Package for Social Sciences, version 13.00 (SPSS Inc., Chicago, Illinois, USA).
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Results |
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Morphology of the cervical column
In the normal group, 14.3 per cent had fusion of the cervical column and 4.8 per cent both fusion and posterior arch deficiency (Table 2). Fusion always occurred between C2 and C3 (Figure 2). No statistically significant gender differences were found in the occurrence of morphological characteristics of the cervical column (females 13.3 per cent, males 16.7 per cent).
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For the condylar hypoplasia subjects, 72.7 per cent had fusion anomalies and 36.4 per cent posterior arch deficiency (Table 2). Fusion occurred between C2 and C3 (45 per cent) and between C3 and C4 (9 per cent). Occipitalization always occurred in combination with either fusion or posterior arch deficiency (36 per cent, Figure 3).
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Morphological deviations of the cervical column occurred significantly more often in patients with mandibular condylar hypoplasia compared with the neutral occlusion and normal craniofacial morphology group (P < 0.05 and P < 0.01, respectively, Table 2). The morphological deviations were significantly more severe in the condylar hypoplasia subjects compared with the normal group (P < 0.01, Table 2).
Head posture and cranial base angle related to the cervical column
The mean values for head posture and cranial base angles in the normal sample are shown in Table 1. The cervicohorizontal and cranial base angles were statistically larger in females than in males (P < 0.01 and P < 0.05, respectively). No statistically significant age differences were found.
For the normal females, cervical lordosis (OPT/CVT, P < 0.01) and inclination of the upper cervical spine (OPT/HOR, P < 0.05) were significantly positively correlated with fusion of the cervical column (Table 3). The cervical column was approximately 5 degrees more curved and the inclination of the upper cervical spine 8 degrees more backwards in the subjects with fusion. Furthermore, the cranial base angle was significantly positively correlated with fusion of the cervical column (Table 3). The cranial base angle was approximately 7 degrees more flexed in the subjects with fusion (Table 3). These associations were not due to the effect of age.
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For the normal males no associations between fusion of the cervical column, head posture, or cranial base angle were found.
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Discussion |
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Even though the groups were small, they provide useful and valid information. It is not possible to extend the two samples as they are unique. The mandibular condylar hypoplasia group is an historic sample collected over a long period of time and consisted of patients with severe condylar malformations. The profile radiographs of subjects with neutral occlusion and normal craniofacial morphology and no medical indications are now difficult to obtain in Denmark because of the Danish law implemented by the national ethical committee system.
Previous studies have found an association between the morphology of C1, atlas, head posture, and the cranial base (Kylämarkula and Huggare, 1985; Huggare, 1991; Sandikcioglu et al., 1994). In the present study, cervical lordosis, inclination of the upper cervical spine, and the cranial base angle in females were significantly positively correlated with fusion of the cervical column. These findings have not been reported previously.
As the head is resting on the spine, determined in prenatal life by the notochord, it may be advisable to examine more closely the early formation of the axial skeleton. The notochord develops in the human germ disc and determines the development of the cervical vertebrae, especially the vertebral bodies and also the basilar part of the occipital bone in the cranial base (Müller and O’Rahilly, 1980; Kjær et al., 1994; Kjær, 1995, 1998; Kjær and Fischer-Hansen, 1995; Kjær and Niebuhr, 1999; Sadler, 2005; Figure 4). Therefore, a deviation in the development of the notochord may influence the surrounding bone tissue in the spine as well as in the posterior part of the cranial base. The para-axial mesoderm forming the vertebral arches and remaining parts of the occipital bone are also formed from notochordal inductions. On post-natal profile radiographs, the bone tissue formed around the notochord are the vertebral bodies and the basilar part of the occipital bone. The common origin of the spine and posterior part of the cranial base is the background for the hypothesis of associations between the cervical spine, head posture, and cranial base.
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Signs of deviations in the development of the notochord could be fusion anomalies and/or posterior arch deficiency of the cervical column as seen in the present study. Fusion of C2 and C3 was associated with posture of the head and neck in terms of cervical lordosis and the inclination of the upper cervical spine. Furthermore, fusion was associated with the cranial base angle. These are observations supporting the hypothesis of associations between structures of common notochordal origin.
The jaws, including the condylar cartilage, develop from tissue that derives from the neural crest. In the first branchial arch the neural crest cells migrate from the neural crest towards the mandible, followed by the cells to the maxilla, and lastly by the cells to the nasofrontal region (Kjær, 1998). The neural crest cells express Hox genes that are homeobox-containing regulatory genes organized in four clusters located on different chromosomes, Hox A, -B, -C, and -D (Acampora et al., 1989; Duboule and Dolle, 1989; Krumlauf, 1994; Ruddle et al., 1999). How the migration of the neural crest cells are influenced by signals from the notochord is still unclear. In previous studies an association has been found between malformations of the upper cervical vertebrae and patients with cleft lip and/or palate (Sandham, 1986; Horswell, 1991; Ugar and Semb, 2001), where the migration of the neural crest cells to the maxillary area might deviate from normal. While the associations between the cervical column and the maxilla are well described, no studies have reported an association between deviations of the cervical vertebrae and the mandible.
In the present study the morphological deviations of the cervical column occurred significantly more often in patients with mandibular condylar hypoplasia compared with those with neutral occlusion and normal craniofacial morphology. One explanation for the association between the mandibular condyle and the cervical column may be signalling from the notochord to the neural crest cells determined for condylar development before the notochord is surrounded by bone tissue and disappears (Müller and O’Rahilly, 1980; Kjær et al., 1994; Kjær, 1995, 1998; Kjær and Fischer-Hansen, 1995; Nolting et al., 1998; Sadler, 2005). Signalling during early embryogenesis between the notochord, para-axial mesoderm, the neural tube, and the neural crest, as described above, are believed to be important for the connection between malformation of the craniofacial structures and the cervical vertebrae.
It was also found in the present study that the pattern of morphological deviations was significantly more severe in patients with mandibular condylar hypoplasia compared with subjects with neutral occlusion and normal craniofacial morphology. Experimental laboratory studies are needed to find an explanation for the different patterns in the two samples.
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Conclusions |
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Morphological deviations and the patterns of such deviations of the cervical column occurred significantly more often in patients with mandibular condylar hypoplasia compared with subjects with neutral occlusion and normal craniofacial morphology. In subjects with normal condylar development, the cervicohorizontal and cranial base angles were statistically larger in females than in males. For females, cervical lordosis, inclination of the upper cervical spine, and the cranial base angle were significantly positively correlated with fusions of the cervical column. This correlation was not found in males.
The cervical column related to head posture, cranial base angle, and condylar malformation has not been described previously. It is suggested that the key to understanding the associations between apparently random structures such as the cervical column, the cranial base, head posture, and the mandibular condyle is the notochord and the common signalling from the notochord forming these craniofacial structures during early embryogenesis.
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Acknowledgement |
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We extend sincere thanks to the students and staff members at the School of Dentistry, Aarhus University, Denmark.
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References |
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-
Acampora D, et al. The human HOX gene family. Nucleic Acids Research (1989) 17:10385–10402.
Björk A. The face in profile. Svensk Tandläkebladet (1947) 40((Supplement 5B) 1).
Björk A. Kæbernes relation til det øvrige kranium. In: In: Nordisk Lärobok i Ortodonti (1975) 4th edn. Stockholm, Sweden: Sveriges Tandläkarförbunds Förlagsförening. 69–110.
Cohen J. A coefficient of agreement for nominal scales. Educational and Psychological Measurement (1960) 20:37–46.[CrossRef][Web of Science]
Dahlberg G. Statistical methods for medical and biological students. (1940) New York: Interscience Publications.
Danish Ministry of Health Order No. 338 1998. Bekendtgørelse om kommunal tandpleje. In: Schultz Grafisk A/S. Copenhagen.
Doboule D, Dolle P. The structural and functional organization of the murine HOX gene family resembles that of Drosophila homeotic genes. European Molecular Biology Association (1989) 8:1497–1505.
Hackney J, Bade D, Clawson A. Relationship between forward head posture and diagnosed internal derangement of the temporomandibular joint. Journal of Orofacial Pain (1993) 7:386–390.[Medline]
Hellsing E, McWilliam J, Reigo T, Spangfort E. The relation between craniofacial morphology, head posture and spinal curvature in 8, 11 and 14-year-old children. European Journal of Orthodontics (1987) 9:254–264.
Horswell BB. The incidence and relationship of cervical spine anomalies in patients with cleft lip and/or palate. Journal of Oral Maxillofacial Surgery (1991) 49:693–697.[Medline]
Houston WJB. The analysis of errors in orthodontic measurements. American Journal of Orthodontics (1983) 83:382–390.[CrossRef][Web of Science][Medline]
Huggare J. A cross-sectional study of head posture and craniofacial growth in children from the north of Finland. Proceedings of the Finnish Dental Society (1987) 83:5–15.
Huggare J. Association between morphology of the first cervical vertebra, head posture, and craniofacial structures. European Journal of Orthodontics (1991) 13:435–440.
Huggare J, Harkness E. Associations between head posture and dental occlusion. Journal of Dental Research (1993) 72:255. (abstract).
Huggare J, Houghton P. Associations between atlantoaxial and craniomandibular anatomy. Growth Development and Aging (1996) 60:21–30.[Web of Science][Medline]
Kjær I. Human prenatal craniofacial development related to brain development under normal and pathologic conditions. Acta Odontologica Scandinavica (1995) 53:135–143.[Web of Science][Medline]
Kjær I. Neuro-osteology. Critical Review of Oral Biology Medicine (1998) 9:224–244.
Kjær I, Fischer-Hansen B. The adenohypophysis and the cranial base in early human development. Journal of Craniofacial Genetic Deviation Biology (1995) 15:157–161.
Kjær I, Nieburh E. Studies of the cranial base in 23 patients with Cri-du-Chat syndrome suggest a cranial developmental field involved in the condition. American Journal of Medical Genetics (1999) 82:6–14.[CrossRef][Web of Science][Medline]
Kjær I, Keeling JW, Græm N. Midline maxillofacial skeleton in human anencephalic fetuses. Cleft Palate-Craniofacial Journal (1994) 31:250–256.[CrossRef]
Kritsineli M, Shim YS. Malocclusion, body posture, and temporomandibular disorders in children with primary and mixed dentition. Journal of Clinical Pediatric Dentistry (1992) 16:86–93.[Medline]
Krumlauf R. Hox genes in vertebrate development. Cell (1994) 78:191–201.[CrossRef][Web of Science][Medline]
Kylämarkula S, Huggare J. Head posture and the morphology of the first cervical vertebra. European Journal of Orthodontics (1985) 7:151–156.
Lee W-Y, Okeson JP, Lindroth J. The relationship between forward head posture and temporomandibular disorders. Journal of Orofacial Pain (1995) 9:161–167.[Medline]
Marcotte MR. Head posture and dentofacial proportions. Angle Orthodontist (1981) 51:208–213.[Web of Science][Medline]
Müller F, O’Rahilly R. The early development of the nervous system in staged insectivore and primate embryos. Journal of Comparative Neurology (1980) 193:741–751.[CrossRef][Web of Science][Medline]
Nolting D, Fischer Hansen B, Keeling K, Kjær I. Prenatal development of the normal human vertebral corpora in different segments of the spine. Spine (1998) 23:2265–2271.[CrossRef][Web of Science][Medline]
Opdebeek H, Bell WH, Eisenfeld J, Mishelevich D. Comparative study between the SFS and LFS rotation as a possible morphogenetic mechanism. American Journal of Orthodontics (1978) 74:509–521.[CrossRef][Web of Science][Medline]
Rocabado M, Johnston BE, Blakney MG. Physical therapy and dentistry: an overview. Journal of Craniomandibular Practice (1982) 1:46–49.[Medline]
Ruddle FH, et al. Evolution of chordate hox gene clusters. Annals of New York Academy of Sciences (1999) 870:238–248.[CrossRef][Web of Science][Medline]
Sadler TW. Embryology of the neural tube development. American Journal of Medical Genetics (2005) 135C:2–8.
Sandham A. Cervical vertebral anomalies in cleft lip and palate. Cleft Palate Journal (1986) 23:206–214.[Web of Science][Medline]
Sandikcioglu M, Skov S, Solow B. Atlas morphology in relation to craniofacial morphology and head posture. European Journal of Orthodontics (1994) 16:96–103.
Siersbæk-Nielsen S, Solow B. Intra- and interexaminer variability in head posture recorded by dental auxiliaries. American Journal of Orthodontics (1982) 82:50–57.[CrossRef][Web of Science][Medline]
Solow B. Guest Editorial: orthodontic screening and third party financing. European Journal of Orthodontics (1995) 17:79–83.
Solow B, Sandham A. Cranio-cervical posture: a factor in the development and function of the dentofacial structures. European Journal of Orthodontics (2002) 14:447–456.
Solow B, Siersbæk-Nielsen S. Growth changes in head posture related to craniofacial development. American Journal of Orthodontics (1986) 89:132–140.[CrossRef][Web of Science][Medline]
Solow B, Siersbæk-Nielsen S. Cervical and craniofacial posture as predictors of craniofacial growth. American Journal of Orthodontics and Dentofacial Orthopedics (1992) 101:449–458.[Web of Science][Medline]
Solow B, Sonnesen L. Head posture and malocclusion. European Journal of Orthodontics (1998) 20:685–693.
Solow B, Tallgren A. Head posture and craniofacial morphology. American Journal of Physical Anthropology (1976) 44:417–435.[CrossRef][Web of Science][Medline]
Solow B, Siersbæk-Nielsen S, Greve E. Airway adequacy, head posture, and craniofacial morphology. American Journal of Orthodontics (1984) 86:214–223.[CrossRef][Web of Science][Medline]
Solow B, Skov S, Ovesen J, Norup P W, Wildschiødtz G. Airway dimensions and head posture in obstructive sleep apnoea. European Journal of Orthodontics (1996) 18:571–579.
Sonnesen L. Ansigtsmorfologi og kæbefunktion (Craniofacial morphology and temporomandibular disorders. With an English summary) (1997) 1–112.
Sonnesen L, Bakke M, Solow B. Temporomandibular disorders in relation to craniofacial dimensions, head posture and bite force in children selected for orthodontic treatment. European Journal of Orthodontics (2001) 23:179–192.
Ugar DA, Semb G. The prevalence of anomalies of the upper cervical vertebrae in subjects with cleft lip, cleft palate, or both. Cleft Palate-Craniofacial Journal (2001) 38:498–503.[CrossRef]
Visscher CM, de Boer W, Lobbezoo F, Habets LLMH, Naeije M. Is there a relationship between head posture and craniomandibular pain? Journal of Oral Rehabilitation (2002) 29:1030–1036.[CrossRef][Web of Science][Medline]
von Treuenfels H. Die Relation der Atlasposition bei prognather und progener Kieferanomalie. Fortschritte der Kieferorthopädie (1981) 42:482–491.[CrossRef]
Watson DH, Trott PH. Cervical headache: an investigation of natural head posture and upper cervical flexor muscle performance. Cephalalgia (1993) 13:272–284.[CrossRef][Web of Science][Medline]
Wenzel A, Højensgaard E, Henriksen JM. Craniofacial morphology and head posture in children with asthma and perennial rhinitis. European Journal of Orthodontics (1985) 7:83–92.
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